A steel ladle functions as a normally portable container for a molten steel melt. The ladle comprises a steel shell lined with a refractory lining for containing the melt. The melt can be stirred by multi-phase electromagnetic stirrers positioned on the outside of the side wall of the ladle, in which case the steel shell is normally made of a non-magnetic steel.
However, if instead of stirring only, it is desired to electrically inductively heat the melt in the ladle there is a problem connected with using the conventional single-phase coil on the outside of the side wall and powered by single-phase AC having a frequency of from 50 to 60 c.p.s. When this is attempted the steel shell wall is also inductively heated, reducing the field intended to heat the melt and causing excessive heating of the ladle shell.
The steel melt is sometimes fed from the ladle into a tundish from which it feeds into a casting mold, and where applicable the term "ladle" can mean a tundish as an equivalent. Also, other metal melts may be considered an equivalent to a steel melt.